Maybe because you like to walk and feel like your are doing squats at the same time. Perhaps you just want to carry the gun grandpa used to win the war. I know, you want to lug around a full sized handgun all day and have to significantly change your wardrobe around it.
I repeat, I can conceal the 1911 in an IWB holster
under a t-shirt. Obviously, it can't be a snug-fitting one, but it's not a baggy one either. There are few occasion when I need to make any significant changes to my wardrobe, even in hot weather.
I'm being sarcastic, obviously. I cannot think of a reason why I, or you, would want to CC a full size 1911. It's only saving grace is its thiness, but there are also polymer framed guns out their just as slim and much lighter. I like 1911s, but they are just not the most ideal CCWs.
As I've said before, weight is a non-issue. If you honestly think
three pounds is
heavy...
Pick a good holster, and you won't even notice it most of the time.
The only polymer guns as thin as a 1911 are much smaller guns, firing smaller calibers. And I CAN think of a good reason why one would want to carry a full size gun -- several in fact: they're much easier to shoot accurately, especially under stress, they have larger ammo capacities, in case you do need it, and they generally chamber more potent cartridges, or at the very least, get more power of the cartridges they fire, by virtue of having longer barrels that impart more velocity. It's a good idea to carry the biggest gun you can manage to conceal without difficulty, because that's the one that gives you the best chance if you ever have to use it.
I cannot think of a reason why I, or you, would want to CC a small gun when a full size one can be carried instead (at least most of the time).